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Alright so I’m new to the site so maybe this question has already been asked. I have a 2002 Yz426f and I want a new exhaust, it has the stock header and silencer and sounds amazing but I’d like a little more from it, I know I want the fmf power bomb header and am kind of undecided on the silencer, I see on fmf’s website that their silencer will add low end and slightly take from top end and the other way around but I’m looking for increases throughout rpm range. I do a lot of trail, hill climbs, jumps, and wheelies so kind of need good performance everywhere in the rpms. My question is what silencer I should get and the jetting I should get for the carb. Thanks

hey guys just picked up a new project bike. Its a 2008 Yz450f with a big bore kit and a stroker crank. The total cc of the engine is now 499. It runs on race gas and will be an absolute monster when shes ready to rip. I will continue to make more videos on the bike so stay tuned Link to the video:

Ok. Last fall after a decently hot day at the track, I noticed coolant leaking from the weep hole on my water pump after pulling into the pits. Ordered an Athena re-seal kit, put it all back together and didn't really get a chance to ride it. 3 weeks ago, went out to the track, and after about 20 laps, it started leaking again. Kept filling it with water to get thru the day, never ran anywhere close to dry or empty, jut a cup or 2 low. Ordered a Hot Rods re-seal kit with bearing and also ordered a new w/p shaft. Did it all again and got it back together, ran it, and as soon as it got to temp, it was leaking out of the weep hole again.

So, what the heck am I missing? I'm totally stumped on this one. Is something wrong with my case cover? Do I need to replace the w/p itself? I'm feeling like I should've just ponied up for the Boysen in the first place, and now it's biting me in the butt. Any help or suggestions is greatly appreciated. Thanks!

Alright guys, my 04 YZ450f runs fine minus some slight backfires when decelerating (need to adjust fuel screw). The other day when I was done checking my valve clearances I changed the oil and filter and put the bike back on the stand, kicked it a few times without the ignition coil in to get some oil flowing got off and noticed a little drip spot on the ground, it was no bigger than a dime so I thought nothing of it. Started the bike with no issues took it for a quick 10-15 min ride, came back to the garage to find out my whole case was soaked with oil and it started pooling in the low spots on the clutch basket side. I cleaned all the oil off and took it out again for 5 mins to try and see where it was coming from, here are my three possible places but nothing directly leads me to believe it’s any of the three either.
1. Decompression plug area
2. Valve cover gasket leak (not really sure because the amount of oil leaking Looks to be a large amount
3. Oil tank (bad weld or cracked weld somewhere
what are you guys thinking?

Hey guys. I could really use your help diagnosing an issue that came up riding today. Bike is a 2013 YZ450F. Well maintained and haven't had any issues until now. Both the oil and coolant are new and levels are to spec.
Issue
After riding for about an hour in the sand dunes, I noticed a grinding going on on the right side of the bottom end (from what I could tell). When I looked to see what was going on my kickstarter was vibrating and grinding really loud. This was a different sound than if you engaged the kickstarter while running. It sounded less "clanky" and more "vibrating/grinding" if that makes sense. Grabbing the kickstarter and moving it didn't help the issue.
When I noticed it, I shut the bike off and gave it a second. Being a few miles deep into the dunes, I had to get it out of there so I started it back up and it seemed fine- no grinding. I headed back to the car and after a few minutes, it came back so I shut it off again, started it back up and nothing. That process happened one or two more times before I made it back to the truck. Seemed to run fine otherwise.
Once I got it back to the truck I started it up and tried to pay more attention to what was going on but it wasn't doing it. I did seem to have more of a metal on metal noise coming from the motor. I started and stopped the bike a few times and after the motor stopped there was a distinct metal clank/grinding noise that happened right after the motor shut of for maybe half a second. This doesn't happen every time.
I tried doing some research and have seen things that make me think it could be the spring that connects to the kickstarter, or the kickstarter stopper plate- but really I have no idea.